*{margin: 0;padding: 0;} 
	nav{
		height:50px;
		background: #333;
		display:flex;
		justify-content: center;
	}
	nav a{
		display: block;
		height: 50px;
		color:#fff;
		line-height: 50px;
		text-decoration: none;
	}
	.banner{
		height: 320px;
		background-color: black;
		background-repeat: no-repeat;
		background-position: center;
	}
	.product{
		display: flex;
	}
	.product a{
		border:1px solid red;
		display:block;
		background-size: 100% 100%;
		width: 200px;
		height: 200px;
		margin-top:20px;
	}
	.product a:nth-child(odd){
		background-image: url(./images/03.jpg);
	}
	.product a:nth-child(even){
		background-image: url(./images/04.jpg);
	}